Thomas Clay is the talented and perhaps even brilliant British film-maker who caused a stir three years ago at Cannes with his debut feature, The Great Ecstasy of Robert Carmichael - an utterly confident, harrowing and finally repulsive movie. I found its technique mesmeric, but was unreconciled to its final scene of arthouse-extreme rape, part of a continuing macho-realist tendency of male directors subjecting female characters to sexual assault at the very end of a highbrow film.

Last year, Clay returned to Cannes with a second film, which is only now getting a UK release: a mysterious, hallucinatory and weirdly enthralling metaphysical essay. It is defiantly unBritish and unparochial, and produced entirely outside the media radar-sweep of the British industry and its public funding bodies. With boldness and entrepreneurial flair, Clay made this in Thailand and, in doing so, fascinatingly absorbed the influence of Thai film-makers such as Joe Weerasethakul and Pen-ek Ratanaruang.

Soi Cowboy takes its name from a red-light zone in Bangkok, and it is a thoughtful and disquieting poetic meditation on the Thai experience of globalisation and its complex relationship with foreigners or "farangs". The film is provocative, and there is one scene of violence that is obliquely rendered, but the film has an elusive, Lynchian dreaminess that will not allow for any easy interpretative pinning-down.

The action is initially filmed in a dull black and white: a fat westerner (Nicolas Bro) and his Thai girlfriend (Pimwalee Thampanyasan) live a torpid life in their claustrophobic Bangkok flat. Long takes and extended "real-time" cinematography - from Weerasethakul's cameraman, Sayombhu Mukdeeprom - follow the couple around as they get on each other's nerves in a non-serious way. The man, evidently a film-maker, slopes off to the supermarket or the mall to buy Viagra or a piece of inexpensive jewellery. The woman hangs out in the apartment playing video games. Nothing much happens. Yet the woman has a complicated family background. We see her telling her brother that she expects her boyfriend to marry her soon and pay a "sin sot", or dowry, of 150,000 baht.

This brother is a gangster working for a sinister Bangkok figure called "uncle". As the movie moves into its second act, it shifts weirdly into colour (a structural flip-over reminiscent of Weerasethakul's Tropical Malady) and we follow him as he carries out an awful errand: he must carry out a hit for a promised bounty of 150,000 baht, money his employer has earned from the bar-girl industry.

Later we see the man and girl from the first act reappear in a kind of nightmarishly ambiguous alternative-universe vision in uncle's bar, this time as prostitute and typical sleazeball customer. That repeated, parallel figure of 150,000 baht gestures at some spiritual selling-out in Thailand's relationship with the west - or perhaps Clay's movie-parable can't be reduced to these terms.

Either way, this is a fascinatingly distinctive, intelligent movie from a director uncompromisingly insistent on cinema as an art form.